Drive arrangement



Nov. 23, 1965 J. G. WALLACE ETAL' ,218,

DRIVE ARRANGEMENT Filed April 6, 1962 INVENTORS. 1 Jam/ l/(uzn: @024! 1.$04 775 v v I Y [3 7 3 39 United States Patent 3,218,878 DRIVEARRANGEMENT John G. Wallace, Branford, and George L. Soltis, Shelton,

Conm, assignors to Dictaphone Corporation, Bridgeport, Conn., acorporation of Connecticut Filed Apr. 6, 1962, Ser. No. 185,619 6Claims. (Cl. 74-424.8)

This invention relates to an improved supporting and driving arrangementfor the transducer head carriage in a dictating machine and the like.

An object of this invention is to provide a rugged and efficientmounting and feedscrew engaging arrangement for a transducer headcarriage.

A more specific object is to provide an improved feedscrew nut engagingarrangement in a machine of this kind.

A further object is to provided a feednut arrangement which is positivein its action and which is relatively inexpensive to manufacture andassemble.

These and other objects will in part be understood from and in partpointed out in the following description.

In a dictating machine such as shown in U.S. patent application, SerialNo. 728,646 (-7180), now patent No. 3,056,606 a belt record is stretchedover and upon a pair of mandrels. Mounted to slide on guide rodstransversely beneath the record is a carriage which supports a recordinghead and a playback head. During recording, as the record is rotated onthe mandrels, this carriage moves slowly across the record with therecording head in contact with it to trace out a close-pitch, helicalsignal track. The carriage is driven by a feedscrew to which, duringthis operation, it is coupled by means of a feednut mounted on thecarriage and locked in engagement with the feedscrew. To permit thecarriage to be shifted manually across the record, the feednut must beunlocked or otherwise disengaged from the feedscrew. The presentinvention provides an improved arrangement for locking and unlockingsuch a feednut. Moreover, this arrangement simplifies the mounting ofthe carriage.

In accordance with the present invention, in one specific embodimentthereof, a toothed feednut is mounted in bearings in a support housingafiixed to the carriage in a dictating machine, such as described above.The teeth of this member engage the threads of the feedscrew so thatwhen the member is locked in its housing the carriage will be driven bythe feedscreW. To provide quick and positive locking of the feednut, oneend of its is tapered and is positioned to engage a mating taperedsurface of the housing in which it is journaled. By shifting the feednutaxially only a very small distance the feednut can be locked verytightly in its housing. Conversely, by shifting the tapered surfacesapart, the feednut is permitted to rotate freely. Advantageously, thefeednut housing has a portion of plastic which bears against thefeedscrew to provide a smoothly sliding support surface. This permitsthe carriage to be supported on only one guide rod, in addition to thefeedscrew, and thereby simplifies mounting of the carriage.

A better understanding of the invention together with a fullerappreciation of its many advantages will best be gained from thefollowing description given in connection with the accompanying drawingswherein:

FIGURE 1 is a perspective View of a portion of a dictating machine witha carriage embodying features of the invention; and

FIGURE 2 is a greatly enlarged section of the carriage showing thefeednut and housing.

The mechanism 10 shown in FIGURE 1 includes two parallel mandrels 12 and14 upon which is stretched a belt record 16. One of these mandrels isdriven by a motor (not shown) and in turn revolves the record in thedirection of an arrow 18. Details of mounting of these mandrels and anarrangement for driving them are given in detail in the above-mentionedpatent.

Positioned beneath the mandrels is a transducer head carriage, generallyindicated at 20. This carriage is mounted for movement across therecord, i.e. parallel to the mandrels, being supported on a guide rod 22and on a feedscrew 24. The carriage in turn supports in front of mandrel14 a playback head 26 which is adapted to engage the record andreproduce sounds recorded on it. A recording head (not shown) is mountedon the carriage beneath mandrel 14. During a recording or playbackoperation, feedscrew 24 is rotated at a fixed speed ratio to mandrel 14,and carriage 20, by being coupled to the feedscrew, is driven slowlyacross the record while it passes longitudinally by the playback andrecording heads.

As seen best in FIGURE 2, carriage 20 has fixed to it a plastic supporthousing 30. The latter embraces and half surrounds feedscrew 24.Positioned in an opening within housing 30 at right angles to thefeedscrew is a feednut 32 whose central part has gear teeth which engagethe thread on the feedscrew. The lower end of feednut 32 is mounted in abushing 34 pressed into housing 30. Projecting beyond the lower end ofthe feednut is a roundheaded screw 36 which is axially threaded into thefeednut. The head of this screw is adapted to be engaged by the inclinedend 37 of a cam arm 38, which can be shifted to the left, as indicatedby an arrow 39, and by means of which the feednut is shifted upward.

The upper end of the feednut is tapered at 40 and is adapted to engage asimilarly tapered met-a1 bushing 42. Pressing downward on the upper endof the feednut is the free end of a leaf spring 44 which is attached tohousing 30 by a screw 46.

Now, when the feednut is shifted upward by the camming action of the arm38 against screw 36, tapered surface 40 will be raised out of intimateengagement with bushing 42. This shifting, which is illustrated inexaggerated form by the dotted lines in FIGURE 2, permits the feednut torotate freely within housing 30. Thus, even though the teeth of the nutcontinue to engage the thread of feedscrew 24, the carriage can befreely shifted back and forth along the feedscrew. Conversely, when arm38 is shifted back to the right to the position shown in FIG- URE 2,feednut 32 is allowed to move down under the force of spring 44, andtapered surface 40 will grip the corresponding surface of bushing 42 andstrongly resist rotation of the feednut. This, of course, locks thecarriage to feedscrew 24 so that when the latter is rotated the carriageis driven across the record. As seen best in FIGURE 1, the rightmost endof arm 38 carries a pin 46 which is engaged by a mechanism (not shown)which in turn is manually operable to shift arm 38 back and forth in thedirection of arrow 39.

Housing 30 is advantageously made of a plastic such as Delrin (an acetalresin) having rigidity, strength and high surface lubricity. Thisenables the housing to slide smoothly along the feedsc-rew andeliminates an additional guide rod for the carriage. Both the feednutand feedscrew are usually made of metal, such as beryllium copper andsteel, respectively.

In an actual machine which has been successfully operated, an axialshift of about .002 inch locks or unlocks the feednut. Surface 40 had a10 taper. Arm 38 was selectively controlled to the right or left by amanually operable mechanism (not shown) on the carriage. The abovedescription of the invention is intended in illustration and not inlimitation thereof. Various changes may occur to those skilled in theart and these may be made without departing from the spirit or scope ofthe invention as set forth.

We claim:

1. In a dictating machine wherein a belt record is mounted upon a pairof spaced mandrels, a carriage for supporting a transducer head and formoving it laterally across the record, a guide rod for supporting oneend of said carriage, a feedscrew for supporting another end of saidcarriage and for driving it, and a feednut housing on said carriageslidably engaging said feedscrew, at least a portion of said housingbeing of plastic having rigidity, strength and high surface lubricity,said housing having recessed in it transverse to said feedscrew afeednut, said feednut being continuously engaged with said feedscrew andbeing axially shiftable into and out of engagement with a locking detenton said housing.

2. The arrangement in claim 1 wherein said detent comprises a taperedbearing which engages a mating surface of said feednut at one endthereof, said feednut being spring-urged into said tapered bearing.

3. In a machine of the character described, an improved carriage drivingand supporting arrangement comprising a feedscrew and a guide rod spacedparallel to each other and supported on a frame, a transducer headcarriage slidably mounted on said rod, a housing on said carriage havinga U-shaped portion embracing said feedscrew, a small diameter elongatedfeednut recessed in said housing at right angles to said feedscrew andin engagement therewith, a tapered bearing in said housing supportingone end of said feednut, said feednut having a mating tapered surface,locking means to urge said nut into locking engagement with said bearingand means to shift said nut axially against said locking means to permitsaid nut to rotate and said carriage to slide freely along saidfeedscrew.

4. The arrangement in claim 3 wherein said housing is of plastic and hasphysical properties substantially like Delrin.

5. An improved drive arrangement comprising a feedscrew, a housingadapted to slide therealong, a feednut rotatably mounted in said housingat right angles to said feedscrew and in engagement therewith, saidfeednut being axially shifta-ble in said housing and being lockedagainst rotation at one end of its axial travel and unlocked forrotation at the other end of its axial travel, and means for axiallyshifting said feednut one way or the other to engage or disengage saidarrangement.

6. The arrangement in claim 5 wherein said housing embraces saidfeedscrew and is at least partly of plastic having rigidity, strengthand high surface lubricity, said housing and feednut having matingtapered surfaces which engage to lock said feednut against rotation whensaid feednut is axially shifted.

References Cited by the Examiner UNITED STATES PATENTS 2,714,010 7/1955Gruber et al. 274-20 2,860,217 11/1958 Bourns 74424.8 3,059,933 10/1962Proctor 274 20 DON A. WAITE, Primary Examiner.

1. IN A DICTATING MACHINE WHEREIN A BELT RECORD IS MOUNTED UPON A PAIROF SPACED MANDRELS, A CARRIAGE FOR SUPPORTING A TRANSDUCER HEAD AND FORMOVING IT LATERALLY ACROSS THE RECORD, A GUIDE ROD FOR SUPPORTING ONEEND OF SAID CARRIAGE, A FEEDSCREW FOR SUPPORTING ANOTHER END OF SAIDCARRIAGE AND FOR DRIVING IT, AND A FEEDNUT HOUSING ON SAID CARRIAGESLIDABLY ENGAGING SAID FEEDSCREW, AT LEAST A PORTION OF SAID HOUSINGBEING OF PLASTIC HAVING RIGIDITY, STRENGTH AND HIGH SURFACE LUBRICITY,SAID HOUSING HAVING RECESSED IN IT TRANSVERSE TO SAID FEEDSCREW AFEEDNUT, SAID FEEDNUT BEING CONTINUOUSLY ENGAGED WITH SAID FEEDSCREW ANDBEING AXIALLY SHIFTABLE INTO AND OUT OF ENGAGEMENT WITH A LOCKING DETENTON SAID HOUSING.